The present invention relates to a coating and developing apparatus, for example, for coating a substrate with a resist solution and developing the substrate, a complex apparatus, and a processing method in the coating and developing apparatus.
In a photo-resist process of semiconductor device fabrication, a resist solution is coated on a surface of a substrate such as a semiconductor wafer (referred to as "a wafer" hereinafter) to form a resist film. After the designated pattern is exposed, the substrate is coated with a developing solution and developed. A coating and developing apparatus is used so far in a series of the above processes.
The coating and developing apparatus is provided with processing units which individually perform a series of processes necessary for coating and developing, for example, an adhesion process for improving resist fixing, a coating process for coating a resist solution, a heating process for heating a wafer after being coated with the resist solution to cure a resist film, another heating process for heating an exposed wafer at the designated temperature, a developing process for developing an exposed wafer, a cooling process for cooling a heated wafer to the designated temperature, and the like.
Incidentally, in order to save installation space, recently an integrated coating and developing apparatus in which the above processing units are vertically multi-tiered is being suggested. Provided almost in a center portion of this type of coating and developing apparatus is a main carrier unit with a vertical carrier system for carrying a wafer in/out from each of the above processing units. Around the main carrier unit, the above processing units are disposed to form a process unit called a process station. A cassette which stores wafers is mounted on a mounting unit called a cassette station disposed on one side of the process station. A sub-carrier unit apart from the above main carrier unit is provided to carry a wafer between the mounting unit and the process unit.
When being carried between the cassette station and the process station, a wafer is not directly carried between the main carrier unit and the sub-carrier unit, but the wafer is usually carried through a delivery unit which can be accessed from both the mounting unit side and the process unit side. Specifically, an exclusive unit for delivery is separately provided in multi-tiered processing units. When a wafer is carried, the main carrier unit and the sub-carrier unit respectively mount the wafer to be carried on the exclusive unit for delivery for a time.
In other words, a wafer to be processed is mounted on the exclusive unit for delivery from the side of the cassette station with the sub-carrier unit. Subsequently, the main carrier unit receives the mounted wafer on the exclusive unit from the side of the process station and carries the wafer to the designated processing unit. Thereafter in each processing unit, the designated processing is performed.
Meanwhile, a wafer which completed the designated processing in each processing unit is carried with the main carrier unit to the exclusive unit for delivery where the wafer is mounted for a time. Subsequently, the sub-carrier unit receives the processed wafer mounted on the exclusive unit and thereafter carries it to the side of the cassette station to be stored in the designated cassette.
Multi-tiered processing units, however, are limited in number of tiers from installation space. If an exclusive unit for delivery is provided, the number of other processing units can not be increased by the space thereof.